It is estimated that the morning glory was introduced to Japan as a Chinese medicine in the Nara era (710-794). In powder form, the morning glory seed is used today as a mild purgative, among other uses, in the practice of Chinese medicine. The morning glory has a round blue flower that is 5 or 6 cm in diameter, as well as three-pointed leaves (trilobed leaves). Though it was at first cultivated for medicinal use, the size and beauty of the morning glory attracted the eye, so that it came to be grown for admiration.
The author used to place the origin of the morning glory somewhere in Tropical Asia or Southeast Asia. After a recent study, however, the author now considers that its origin was probably in Tropical America. The morning glory, Ipomoea nil, is distributed broadly across the world's tropical zones. Recently the author cultivated wild and local strains from East and Southeast Asia, West Asia, Australia, South America, Central America, and Africa, and then investigated the characteristics of these strains.

The general characteristics of the morning glory, Ipomoea nil, are as follows.

The seed is black and has short hair. The hypocotyl has a reddish tinge. The cotyledon has stalks that connect it at two points to the hypocotyl. The lobe of the cotyledon is called the ear. The leaf has three points and is composed of a main lobe and side lobes. It is connected to the stem through the leaf stalk (petiole). The stem is dark brown and hairy. The five petals are united to become the synpetal corolla, which is funnel-shaped. The corolla is blue and the flower tube is white. The central band region of a petal is called the midpetaline band or You. There are five sepals and five stamens, the flower diameter is 5-6 cm, the pistil has three carpels, and each ovary has three locules. Two ovules are attached to the inside wall of each locule. Therefore, the pistil has three locular and six ovular ovaries. When all six ovules are fertilized, they develop into a total of six seeds. The flower formula is K 5 C (5) A 5 G (3). The inflorescence of the morning glory is a dichasium; one flower grows in each axil of two bracteoles of the terminal flower. Furthermore, the next flowers grow in the axils of the second flower. However, it is rare to grow five flowers in one inflorescence. There are epidermal hairs on the stem, the upper and lower surfaces of the leaf, the petiole, and the calyx.